The present invention relates to a land-use cycle provided with a moving fulcrum type leverage and adapted to be propelled by human power, e.g., by foot operation.
A conventional bicycle is designed so that a user can rotate a chain gear by alternately working cranked pedals, which are fixed individually to the opposite sides of the shaft of the chain gear with a phase difference of 180 degrees, by both his feet and transmit this rotation to a rear wheel by means of a chain, thereby propelling the bicycle.
A torque generated in the shaft of the chain gear can be represented by the product of the distance from the shaft to each pedal and a force in the direction of a tangent to the path of rotation of each pedal. Since the strength of a user's leg is limited, the distance from the shaft of the chain gear to each pedal must be made relatively long in order to increase the torque.
Since the diameter of the path of rotation of each pedal of the conventional bicycle is settled on the basis of the length of a standard user's leg, however, it is so hard to work the pedals that the operating efficiency and stability are poor if the diameter of the path is made longer than the existing one.
Moreover, the chain, which is used to transmit the rotation of the chain gear to the rear wheel, may possibly be disengaged from the chain gear or broken, so that it is awkward to handle and requires use of an all-over cover, thus involving a lot of problems.